Screen printing apparatus



United States Patent [72] Inventors Roy M. Harwell, Jr.; 2,624,276 1/1953 Klopfenstein 101/ 123 David W. Yoder, Gastonia, North Carolina2,704,510 3/1955 Walsh 101/123 [21] Appl. No. 690,656 2,747,502 5/1956Gattuso 101/126 [22] Filed Dec. 14,1967 2,866,404 12/1958 Laupman101/123 Patented Dec. 8, 1970 2,881,700 4/1959 Podgor... 101/126 [73]Assignee Harwell Enterprises, Incorporated 2,963,964 12/1960 K1ump....101/ 123 Gastonia, North Carolina 3,160,092 12/ 1964 Eisen 101/ 124 acurporauon of North Carolina Primary Examiner-William B. PennAttorney-Dominik, Knechtel & Godula [$4] SCREEN PRINTING APPARATUS 6Claims, 18 Drawing Figs.

[52] U.S.Cl. 101/123 TRACT; A screen-squeegee printing apparatus inwhich j g B41] 27/00 relative reciprocatory movement between the screenand Field of Search 101/123, squeegee is ff t d by a k h ft through arack and pinion 124, 126,114, 129 connection. The apparatus isspecifically characterized by: mechanism for adjusting the relativecontact pressure between [56] References (med the screen and squeegee;mechanism for effecting right angu- UNITED STATES PATENTS lar engagingmotion between the screen and squeegee at the 1,468,384 9/1923 Hahn101/123 beginning of the printing stroke and right angular separation1,840,073 1/ 1932 Williams.. 101/ 123 motion at the end of the stroke;mechanism for adjusting the 2,039,909 5/1936 Kem et al 101/ 123 strokelength; and rotatable mechanism movable coaxially of 2,571,685 10/ 1951DAutremont 101/ 123 the crankshaft for actuating and locking said strokeadjusting 2,581,775 1/1952 Wade 101/123 mechanism in each adjustedposition.

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SHEET 1 OF 5 INVENTORS: w M. MARWELLJEH N DAVID W-YODE PATENTEB DEC 8I970 SHEET 2 BF 5 INVENTOR$I M. HARWELL, JR. a DAWD W; Yonaa PATENTEUBEE 8 I971] SHEET 3 0F 5 INVENTORS'. Row HRRWELLAP... w Dawn W-YQDERINVENTORS M. HARWELL, Je.

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PATENTED DEC 8 I970 sum 5 or 5 Row Dawn W. Yo

SCREEN PRINTING APPARATUS This invention relates to a screen squeegeeprinting press and more particularly to a machine for applying indiciaor printed matter to various types of articles of commerce.

It is an object .of this in invention to provide a machine of graph, inwhich the adjustment of the stroke and relative screen squeegee speedmay be effected by rotating the coaxial mechanism, and wherein eachadjustment may be releasably locked or fixed by moving the mechanismaxially thereof.

It is yet anotherobject of the invention to provide a screen squeegeeprinting mechanism which is capable of effecting right angular engagingmotion between the screen and squeegee at the beginningof the printingstroke and right angular separation motion atthe end of the stroke.

It is a further object of the invention to provide a mechanism foryieldingly exerting pressure between the screen and squeegee during thecontact or printing stroke, in combination with means for adjustingthispressure.

Some of the objects of the invention having been stated, other objectswill appear as the description proceeds when taken in connection withthe accompanying drawings, in t which:

FIG. 1 is a side elevational view of a printing apparatus, embodying theinvention; j

FIG. 2 is a sectional planview taken along line 2-2 in FIG. 1;

FIG. 3 is a sectional planview taken along line 3-3 in FIG.

FIG. 4 is a sectional plan view taken along line 4-4 in FIG. 1;

FIG. 5 is a top plan view of FIG. 1, showing the squeegee assemblypositioned at the midpoint of the screen during the printing stroke;

FIG. 6 is an elevation of the left. hand end of FIG. 1; FIG.6A is anelevation of the upper right end of FIG. 1; FIG. 7 is a sectional detailview .taken along line 7-7 in FIG.

\ FIGS. 4 and 5, showing the screen in contact with the squeegee;

FIG. 8 is a sectional detail view taken along line 8-8 in FIG. 5,showing mechanism for adjusting yielding pressure between the screen andsqueegee;

FIG. 9 is a sectional planview taken along line 9-9 in FIG. 1, showingdetails of the screen squeegee stroke adjusting mechanism and the meansfor locking the latter mechanism in each adjusted position;

FIG. 10 is an isometric detail view of certain elements shown in FIG. 9;

Fig. 11 is a plan view of a modification of the device shown in FIGS. 1and 5;

FIG. 12 is a schematic electrical wiring diagram of the invention;

FIGS. 13 through 17 are five diagrammatic views of the limit switch camswhich, in combination with the circuitry shown in FIG. 12, automaticallycontrol the printing apparatus; FIG. 13 is a view of limit switch camLSSB which controls the vertical movement of the screen and squeegee;

FIG. 14 is a view of limit switch cam LS4B which controls lateralscreen-squeegee printing stroke;

FIG. 15 is a view of limits witch cam LSlB whichcontrols, in combinationwith cams [.828 and LSSB, the vertical screen-squeegee movement at theend of the printing stroke;

FIG. 16 is a view of limit switch cam LS2B; and

FIG. 17 is a view of limit switch cam LS3B which controls the operationof the foot pedal switch.

Referring more particularly to the drawings, the numeral 10 denotes theframework of the apparatus generally, said framework supporting a screenassembly 11, a squeegee assembly 12, a cable assembly 14, a rack andpinion assembly 15 for driving the cable assembly, a lockable strokeadjusting assembly 16, a motor or prime mover 17 for driving theassemblies, and the circuitry for automatically controlling theoperation of the above elements.

SCREEN ASSEMBLY The screen assembly 11 is composed of a screen 20supported in cantilevered position from upper and lower longitudinalshafts 21 and 22 by means of brackets 23, 23 (FIGS. 4- -7). The shafts21 and 22, in turn, are supported upon the free end portions oftransverse levers 24, 24 and 25, 25 respectively; and the pivoted endsof the levers 24, 24 and 25,

25 are respectively secured upon an upper longitudinally disposed shaft26 and two longitudinally aligned hubs 27, 27.

Shaft 26 has levers 24, 24 fixed thereto and is also mounted framework.

It will be observed from FIGS. 4-7 that the longitudinal axes of shafts21, 22 and 26 and the axis of aligned hubs 27, when viewedfrom the ends,are the corners of a quadrangle having parallel opposite sides. Thus,when the screen assembly is in lowered bold line position the quadranglehas the shape of a rectangle and when the assembly is in the raiseddotted line position the quadrangle has the shape of a parallelogram. Bymeans of this arrangement, the supported screen 20, as well as thesqueegee assembly later described, will have parallel vertical motion atthe. beginning and at the end of the printing stroke.

SQUEEGEE ASSEMBLY FIGS. 5-7illustrate the screen and squeegee assemblies11 and 12 in contacting relationship at the midpoint of the print ingstroke. In this position the lower surface of the screen 20 is in faceto face contact with the upper surface of an article or object 28 to beprinted, said object being removably supported upon a base 29. I t

The assemblies 11 and 12 rise and fall simultaneously but at differentrates of travel. For example, as the assemblies move upwardly fromcontacting position at the end of the printing stroke, the squeegee orwiper 30 travels faster than screen 20 and therefore becomes separated;and at the same time, the screen separates from the object. 28.Similarly, at the beginning of the. machine cycle, both assemblies moveverti cally downwardly at said different rates of travel until thescreen is in contact with the screen thereabove, after which thesqueegee is moved laterally to effect the object 28 and the squeegee isin .contact with the screen thereabove, after which the squeegee ismoved laterally toeffect the printing stroke.

Squeegee assembly comprises the wiper 30, a wiper holder 31, ahorizontal wiper supporting rod 32, and a mounting bracket 33 for therod(FIGS. 4-8). Holder 31 is adjustably mounted upon rod 32 by means of setscrews 31a, which rod is pivotally secured as at 35 to bracket 33, saidbracket being pivotally supported as at 36 and 37 upon the free ends ofupper and lowerlevers 38 and 39 respectively. Upper lever 38 is slidablymounted upon said longitudinal shafts 21 and 26 (FIGS. 5 and 7) and thelower relatively short lever 39 is slidably mounted. upon saidlongitudinal shaft 22 FIGS. 4, 5, 7

1 and 8). Since the swingable pivots 36 and 37 are equidistantly spacedfrom the respective centers of rotation 26 and 27, the bracket 33, rod32 and wiper 30 will remain parallel to their respective startingpositions during vertical movement.

SCREEN-SQUEEGEE PRESSURE ADJUSTMENT MEANS The pressure between screen 20and squeegee or wiper blade 30 may be adjusted by manipulating screws 40and 41, said screws being threadably secured in mounting bracket 33 53,55, 57, 56 and 17a.

(FIGS. 68) and disposed respectively below and above a swingable portionof rod 32. The upper end of screw 40 adjustably limits rotation of rod32 and the blade 30 toward the screen, whereas the lower end of screw 41adjustably exerts downward pressure against a compression spring 41awhich, in turn, yieldably applies the pressure upon rod 32 to press thewiper against the screen.

SCREEN-SQUEEGEE RISE AND FALL ACTUATING MECHANISM The screen andsqueegee assemblies 11 and 12 are raised and lowered by theoscillationof longitudinal shaft 26 (FIGS. 5, 6, 6A and 7). One end ofshaft 26 has a lever 42 fixedly secured thereon, the free end of whichhas a tension spring 43 connected thereto and normally tending to rotatethe assemblies toward the dotted line positions shown in FIGS. 6 and 7.The opposite end of shaft 26 has actuating lever 44 fixedly securedthereon, said lever having its free end pivotally connected as at 45 tothe upper end of link 46. The lower end of link 46 is pivotallyconnected to disc 48 as at 47, the disc being secured on shaft 49extending through gear box 50. The gear box is drivably connected tomotor 17 by means of gear box shaft 53, pulley S3 fixedly secured on thelatter, pulley 56 on motor shaft 17a, and belt 57 on pulleys 53 and 56.Thus the motor 17 oscillates shaft 26 and assemblies 11 and 12 by meansof a connection comprising elements 44, 46, 48,49, 50,

CABLE ASSEMBLY The cable assembly 14, described below, is employed toreciprocate the squeegee assembly 12 longitudinally of shafts 21, 22 and26 (FIGS. 1 and 3--7). Lever 38 of assembly 12 has a downwardlyextending Y shaped bracket 60 pivotally secured thereto as at 61, thelower end of said bracket being secured to an intermediate tensionedportion of a flexible cable 62 by means of clamp plate 63 and bolts 64.Cable 62 extends horizontally in opposite directions from bracket 62,through the aligned hubs 27, 27, then over and downwardly from guidewheels 66, 66, then partially around and horizontally from guide wheels67, 67 to a helically grooved drum 68. The end portions of the cableextend at least partially around the drum and in opposite directions,the ends of said portions being secured to the drum as at 69 and 70. Bywinding the cable end portions around the drum in opposite directions,the oscillation of the drum willunwindone portion while winding theother and vice versa thereby causing brackets 38 and 60 and the squeegeeassembly 12 to reciprocate. Drum 68 is fixedly secured on transverseshaft 71 rotatably mounted in framework 10.

Instead of attaching the cable end portions to the drum 68 at points 69and 70, it is evident that one or more helical turns of the cable aroundthe drum would cause the cable to frictionally adhere securely to thedrum and prevent slippage.

RACK AND PINION ASSEMBLY The rack and pinion assembly 15 is employed toa oscillate drum 68 of cable assembly 14. A pinion 74 on shaft 70 mesheswith the teeth of a longitudinally extending rack 75 (FIGS. 1, 3 and 9),the opposite endof said rack being pivotally connected as at 76 to anadjustment slide 87 of the throw adjustment and lock assembly 16 to bedescribed in the next section.

The teeth of rack 75 are held in mesh with the teeth of pinion 74 bymeans of a bracket'swingably mounted upon shaft 70 and consisting ofconfining rollers 78 and spaced plates 79, 79.

During operation, the point of attachment of the rack 75 to the assembly16 is disposed eccentrically of a main drive shaft 77 upon which thelatter assembly is mounted (FIG. 1). The slide plate 87, eccentric pivot76, and the main drive shaft 77, therefore, combine to serve as acrankshaft for the rack and pinion assembly 15.

LOCKABLE STROKE ADJUSTMENT ASSEMBLY The stroke or throw adjustmentassembly 16 simultaneously controls the speed and back and forth motionof rack 75, drum 68, and squeegee blade 30. This stroke may be adjustedby varying the eccentricity of rack pivot 76 relative to the center ofdrive shaft 77 (FIGS. 1, 3, 9 and 10) as described below.

Drive shaft 77 is rotatably mounted transversely on framework 10 and hasa bracket 82 secured on one end thereof. A sprocket 83 is also mountedupon the end of shaft, said sprocket being secured to bracket 82 bymeans such as stud bolts 84. Bracket 82 is provided with parallelguideways 85, 85 which slidably confine the above mentioned adjustmentslide 87 for movement diametrically of shaft 77. Since rack 75 ispivoted to slide 87 as at 76, the diametrical adjustment of the positionof the slide will vary the eccentricity of pivot 76 and hence thestroke.

The diametrical movement of slide 87 and pivot 76 is effected by meansof a rack 90 integral with the slide, a pinion 91 intermeshing with therack, a rod 92 upon which the pinion is fixedly secured, and a knob 93on the end of the end of the rod opposite the pinion end, said rod,pinion and knob being rotatable and coaxially movablerelative to driveshaft 77. A spring 94 is confined upon rod 92 between knob 93 andframework 10, which spring normally urges the rod, knob and pinionaxially to an adjusted locked position (FIGS. 3, 9 and 10), at whichtime, the pinion not only meshes with rack 90 but also with a secondrack 95 integral with slide 87.

It will be observed that the teeth of rack 90 are longer than those ofrack 95 and, therefore, when the knob 93 is pressed to move rod 92 andpinion 91 axially of the drive shaft 77, the pinion will remain engagedwith rack 90 but become disengaged from rack 95. With the pinionengaging only the rack 90, rotation may be imparted thereto to adjustthe slide 87 and rack pivot 76 diametrically of the drive shaft; andwhen the desired adjustment has been made, the release of pressure uponknob 93 will permit spring 94 to return the pinion and rod axially tolocked position as shown in the drawings.

DRIVE SHAFT ACTUATING MECHANISM Drive shaft 77 and the sprocket 83thereon are driven by motor 17 through a connection comprising motorpulley 97. belt 98, pulleys 99 and 100 of variable speed drive unit 101,pulley 103 on transverse shaft 104, gear 105 on shaft 104, gear belt106, gear 106 on transverse shaft 108, sprocket 109 on shaft 108, andsprocket chain 110, all of said elements being serially connected in theorder named.

Variable speed unit 101 may be adjusted to a desired speed transmissionfrom a manual control knob and through a serially connected chain ofelements (FIGS. l3) such as sprocket 114 on shaft 114a, sprocket chain115, sprocket 116 and worm gear 117 on shaft 118, and worm 119 on shaft121. The above speed variation determines the speed of drive shaft 77and the elements driven thereby.

ELECTRICAL CONTROLS The connection between motor 17 and thescreen-squeegee rise and fall mechanism, namely, elements 17a, 56, 57,S5, 53, 49, 48, 46, and 48, is controlled by electric clutch and brakeunits 124 and 125 respectively, said units being mounted concentricallyshaft 53 and actuated by a relay CR2 (FIGS. 3, 6 and 12). The relay CR2has a normally open switch 127 and an alternately operable normallyclosed switch 128, which switches disengage clutch 124 while applyingbrake 125 and vice versa. The operation of relay CR2, in turn, iscontrolled by foot pedal switch 137 and by limit switch assemblies LS4andLSS on gear box shaft 49.

Similarly, the series of elements between motor 17 and drive shaft 77 iscontrolled by clutch unit 130 and brake unit 131, said units beingconcentrically mounted about shaft 108 and actuated by relay Cr1 (FIG.12). Relay CR1 has normally open and normally closed switches 132 and133 respectively which are alternately operable to disengage clutch 127while applying brake 128 and vice versa. The operation of relay CR1, inturn, is controlled by limit switch assemblies LS1, LS2 and LS3 on maindrive shaft 77 (FIGS. 3 and 12).

FIG. 17 further illustrates the construction of limit switch LS3 whichis typical of the outer limit switches mentioned above. Switch LS3comprises relay LS3A, a swingable arm 139 pivoted to the relay, and aroller 140 on the free end of the arm and engageable with the peripheryof switch cam LS3B.

FIG. 12 is an electrical wiring diagram showing how relays CR1, CR2,limit switches LS1 through LS5, clutches 124, 127, brakes 125, 128, andfoot pedal switch 127 are connected to motor 17 and to one another toautomatically: (a) vertically lower the screen and squeegee at thebeginning of an operating cycle, that is, from dotted line position tobold line position as shown in FIGS. 6 and 7;-(b) move the squeegeelaterally of its vertical path of travel to effect a printing stroke;(c) verti cally raise squeegee and screen at the end of the stroke; (d)move the raised squeegee in the reverse direction to that of theprinting stroke to starting position and to complete the operatingcycle.

Current is supplied to motor 17 through lead wires 143 and i 144, thelatter wire having therein an off-on power switch 145 and an off-onmotor switch 146. At the beginning of the operating cycle, the roller140 of limit switch LS5 rests in notch 148 of cam LSSB (FIG. 13). Alsoat this time, the roller 140 of limit switch LS4 is resting upon its camelement 150 (FIG. 14). Then upon closing the foot pedal switch 137,current is supplied to switches 127 and 128 of relay CR2, which relayreleases brake 125 and causes clutch 124 torengage to thereby permitmotor 17 to rotate limit switch cams LS4B and LS5B for one halfrevolution. At the completion of this partial revolution, roller 140 oflimit switch LS5 engages notch 149 in the associated carn-LSSB (FIG. 13)to apply brake 125 and disengage clutch 124. During the above partialrevolution as above described, the squeegee and screen assemblies 11 and12 are lowered tocause the squeegee and screen to contact one anotherand to cause the screen and object 128 to also make contact as shown inFIGS. 6 and 7.

Immediately before completion of the abovepartial revolu tion, butsubsequent to contact between the screen and squeegee, the element 151of cam LS4B engages the associated limit switch roller 140 to therebysupply current to switch switchs switches I32 and 133 of relay CR1,which switches cause clutch 127 tobecorne engaged and brake 128 tobecome released and thereby permit one-half revolution of drive shaft77. This partial revolution of the drive shaft will impart lateralmovement to the squeegee 30 to effect the printing stroke; and atthe endof this stroke, the roller 140 of limit switch LS1 will engage notch 153in cam LSIB (FIG. to operate clutch 127 and brake 128 and stop driveshaft 77.

At the end of the partial revolution of cam LSlB, the limit switch LS2is energized momentarily to operate relay CR2 I which, in turn, operatesclutch 124 and brake 125 to cause motor 17 to rotate switch cams LS4Band LS5b one-half revolution, thereby raising the squeegee and screenassemblies 11 and 12 to the dotted line noncontacting position such asshown in FIGS. 6 and 7 and at the end of the printing stroke.

Finally, and at the completion of the last named partial i revolution ofcams LS4B and LSSB, the cam element (FIG. 4) causes the relay LS4A 4A tobe energized which, in turn, will actuate CR1, clutch 127 and brake 128to rotate drive shaft 77 and cam LSlB one-half revolution to thestarting position and at the end of the operating cycle.

Briefly stated, when roller 140 of switch LS1 is in notch of cam LSlB asshown in FIG. 15, the relay CR1 is deenergized and the roller occupiesthe dotted line position relative to the notch, the relay is closed, thebrake 128 is off and clutch 127 on. At the end of the printing stroke,the roller140 of switch LS2 is in notch 156 of cam LSZB (FIG. 16), atwhich time, relay CR2 is closed, brake 125 off and the rise and fallclutch 124 on to raise the screen and squeegee to noncontactingpositions. At the end of the operating cycle, the roller 140 of switchLS3 is in notch 157 of cam LS3B (FIG. 17), at which time, the foot pedalswitch 137 will operate only in this position to start a new cycle. Whenroller 1400f switch LS5 is in notch 148 of cam LSSB (FIG. 13), the relayCR2 is at rest, clutch 124 disengaged, and brake 125 on; and when thisroller 140 is in the dotted line position relative to notch 140, theclutch is engaged and the brake off. When the roller 140 of switch LS4is resting on either of cam elements 150 or 151 as shown in FIG. 14, animpulse is imparted to relay CR1 to start rotation of drive shaft 77.

FIG. 12 shows the circuitry which electrically connects the abovedescribed elements CR1, CR2, LS1 through LS5, 124, 127, 125, 128, 137and 17 in a manner to accomplish automatic operation of the invention.These elements comprise comprise conduit and related elements 160through 179.

MODIFIED FORM FIG. 11 illustrates a construction in which the squeegeeassembly 12a remains laterally stationary while the screen assembly 11areciprocates. The squeegee assembly is fixedly secured to shaft 26 bycollars 122 while the screen assembly is slidably mounted upon shaft 21.Reciprocatory motion is imparted to assembly 11a by cable 62 through aconnection comprising the aforementioned Y-yshaped bracket 60 and asecond Y-shaped bracket 12 3.

OPERATION The machine is put into operation by turning on power switch145 and then turning on motor switch 146 (FIGS. 12- -17).

To start an operation cycle, the foot. pedal switch 137 is depressed,closing a circuit through LS3A which is closed at start position bylever 139 resting in LS3B (FIG. 17), thereby closing relay CR2. Theclosed relay CR2 releases brake 125 and closes clutch 124 to lower therise and fall mechanism from dotted line to bold line position (FIGS. 6and 7) to printing position at the left hand edge of screen 20 (FIG. 5).I

- Atthis time, gear box 50 has been rotated to position cam LSSB fromstarting position. This cam LS5B maintains contact through LSSA to holdrelay CR2 energized, which relay holds clutch 124 closed to rotate gearbox 50 through this 180. Just before completing this 180 travel of camLSSB, the cam 150 on LS4B closes LS4A momentarily to close CR1 which, inturn, opens brake 128 and closes clutch 127 to start the printing strokefrom left to right in FIG. 5. When LSSB completes its first 180 travel,it releases LS4A and CR1 is thereby maintained in closed position byLSlA and its controlling cam LSlB during the printing stroke.

The printing stroke is completed when drive shaft 77 has travelled 180and LSlA has been opened by cam LSlB (FIG. 15) which, in turn, opens CR1to close brake 128 and open clutch 127. At the end of the printingstroke, the cam LS2B has turned to the position shown in FIG. 16. Atthispoint, the

limit switch LS2A is closed which, in turn, closes CR2 to close clutch124 and open brake 125 thereby rotating gear box 50; the latter rotationraises the screen 20 and squeegee 30 from contact with workpiece 28 asshownin dotted lines in FIGS. 6 and 7.

. At this time, cam LSSB is rotating and will turn 180. Near the end ofthis rotation, cam LS4B momentarily closes limit switch LS4A by contactwith lobe 1.51 (FIGS. 14 and 15) and closes CR1, thereby starting maindrive shaft 77 concurrently with the closing of clutch 127 and theopening of brake 128. The drive shaft 77 turns 180 which brings it tothe end of the operating cycle, or to the starting point for asucceeding operating cycle.

In the drawings and specification preferred forms of the invention havebeen disclosed; and although specific terms are employed, these are usedin a descriptive sense and not for purposes of limitation, the scope ofinvention being defined in the following claims:

We claim:

1. A printing apparatus having a screen member, a squeegee member andmeans for imparting relative reciprocatory movement between said screenand squeegee members between starting and final printing strokepositions, said means includ ing a cable to which one of said screen andsqueegee members is mounted, crankshaft means having a driven rotarymember, an elongated connecting element repositionable meanseccentrically and adjustably connecting one end of said elongatedconnecting element to said driven rotary member whereby said elongatedconnecting element is reciprocated by said driven rotary member,translation means coupled to the opposite end of said elongatedconnecting element and to sald cable translating the reciprocation ofsaid elongated connecting element to said cable to reciprocate saidcable, said adjustable to change the eccentric mounting of saidelongated connecting element to said driven rotary member along an axissubstantially normal-to the axis of said driven rotary member to changethe strokeof said elongated connecting element and hence the relativereciprocatory movement between said screen and squeegee members.

2. A printing apparatus-as defined in claim 1 wherein saidrepositionable means includes a-rack means slidably mounted on saiddriven rotary member, said elongated connecting element being pivotablymounted to said rack means, a pinion positioned along the axis of saiddriven rotary member and engaged with said rack means, said pinion beingeffectively disengageable from said rack means to allow said rack meansto be moved and positioned to engage said rack means and fix theposition of the rack means relative to said rotary member.

3. A printing apparatus as defined in claim 2 wherein said rack meansincludes two racks spaced from one another a distance to accommodate thepinion when effectively engaged therebetween.

4. 4 A printing apparatus as defined in claim 1 wherein said translationmeans comprises an oscillatable drum, said cable being under tension andone of said squeegee and screen members being secured to an intermediateportion of said cable thereof, said cable extending in oppositedirections from said one of said squeegee and screen member securedthereto and being wound around at least a part of the drum periphery soas to be reciprocated by said drum as the latter is oscillated, saidelongated connecting element being coupled to and oscillating said drumduring reciprocation of said elongated connecting element, to therebytranslate the reciprocation of said elongated connecting element to saidcable.

5. An apparatus as defined in claim 4 wherein said oscillatable drum ismounted on a shaft, a gear is fixed on said shah, and said elongatedconnecting element having a rack portion engaging said shaft gear sothat reciprocation of said elongated connecting element oscillates saidshaft and said drum mounted thereon.

6. A printing apparatus as defined in claim 1 wherein said squeegee andscreen members are mounted to a parallelogram linkage which permits saidmembers to move in a substantially normal path relative to the surfaceof the screen, one member of said parallelogram linkage comprising anintermediate portion of said cable, said cable including portionsturnable around spaced rollers respectively located generally at thestarting and final printing stroke positions of said apparatus, and saidcable having another portion joined to said crankshaft means.

